Billions of photos are shot every year, and about the toughest thing a photographer can do is invent an original, deeply personal, instantly recognizable visual style. In the early 1990s, Wolfgang Tillmans did just that, transforming himself into a new kind of artist-photographer of modern life. He’s now so widely imitated and all-purpose that -- like Pollock’s tangles or Warhol’s colors -- Tillmans’s style is everywhere. It’s part of the culture.